1. Field of the Invention
The present invention relates to a multi-wavelength light-emitting module, and particularly relates to a multi-wavelength light-emitting module with high density electrical connections.
2. Description of the Related Art
As a method for forming a color photograph or a color print, there is a method for forming an image, such as a picture or a character, on a photosensitive sheet by exposing the sheet. There are different types of photosensitive sheets, for example, a photosensitive sheet employing a multi-layer color development method, in which three layers of photosensitive emulsions with different color sensitivities are layered on a single supportive sheet thus forming a photosensitive member, a photosensitive sheet that employs a film in which each emulsion layer contains a pigment and a developing agent so that the film is capable of being exposed and developed simultaneously, and the like.
A still another photosensitive sheet called Cycolor medium, as shown in FIG. 1, which employs, as a photosensitive material, microcapsules (cyliths) (3a, 3b, 3c) that contain different chromogenic substances and different photoinitiators. In the Cycolor medium la, a thin supportive body 2 formed from, for example, polyester, is coated with a photosensitive material layer 4 containing numerous cyliths of a very small size. When exposed to light, cyliths harden so that only the cyliths of a specific color are activated, and the cyliths are ruptured by pressurization, and then developed, thereby forming an image of a predetermined color. Other photosensitive sheets have different color development principles, but need to be exposed to exposure light of the color of an image or its complementary color to form an image.
In widely used methods for exposing a photosensitive sheet, white light is split into three primary colors by a filter or the like, and images are formed using the individual primary colors, and then combined to form an image of predetermined colors or an image of their complementary colors on the photosensitive.
Another technology has recently been developed, as disclosed in Japanese patent application laid-open Nos. Hei 5-211666 and Hei 5-278260, in which LEDs or lasers that emit red light, green light and blue light are employed as light-emitting sources, and the light-emitting sources are controlled so that. an image of predetermined colors is formed on a photosensitive sheet and the sheet is thereby exposed.
However, in an exposure apparatus employing LEDs or lasers as light sources as disclosed in Japanese patent application laid-open Nos. Hei 5-211666 and Hei 5-278260, a lens system is employed to converge light emitted from the LEDs or lasers onto a medium. To control colors in the unit of dots, it is necessary to employ expensive optical systems that require a large installation space, such as a scanning optical system, a micro-lens array, and the like. The micro-lens array and lens groups constituting the scanning optical system have a loss in light transmission, so that only a portion of the light emitted from the LED or laser light sources reaches the photosensitive sheet (medium). Therefore, in some cases, LEDs are not sufficient to provide an amount of light required for exposure of a photosensitive sheet. In other cases, the printing rate must be reduced and the printing time must be increases in order to secure a sufficiently long exposure duration. In addition, an optical system employing lenses requires a large installation space, and is costly, so that a printing apparatus becomes large and costly.